1) Field of the Invention
The invention relates to the automated picking up of objects using a robot. More specifically, the invention relates to the automated picking up of objects which are randomly disposed in a bin.
2) Description of the Prior Art
In some industrial applications, in an assembling or packaging factory for example, it is required to recognize and pick up objects randomly arranged in a bin, a box or the like. The objects to be picked up may be mixed up in the bin with objects that are not useful at a given stage of the industrial process. A vision system is generally used to recognize the useful objects to be picked up and to determine their position in the bin to guide a robot which is used for grasping a selected object, to pick it up and place it in an arranged or predetermined position, such as in a shipping box for example. The bin-picking system first needs to select which object to pick up based on the information provided by the vision system.
Many picking up jobs are currently only doable by humans. One difficulty with the picking up of randomly arranged objects is that the objects may be piled up thus preventing the robot to reach some objects obstructed by other useful or unuseful overlapping objects in a given pile arrangement. The picking up system is required to recognize and select unobstructed objects but is prevented to do so by the overlapping objects.
If the objects to be picked up are disposed in a bin, a further difficulty results from the walls of the bin which may be mechanical obstacles in the reaching of an object by the robot. In some applications, the objects can only be grasped from one predetermined orientation relative to the object because the object is not symmetric and/or because it is required that the gripper of the robot grasps the object using specific features on the object, such as a hole, a post, etc. If the object is incorrectly oriented and/or close to the walls of the bin, the gripper, even if articulated to adjust its orientation, may not be able reach the object as it would hit the walls of the bin while moving to the object.
To circumvent those problems, the objects to be picked up are conventionally orderly arranged on a tray, a conveyer or a bin such that the objects are not piled up on one another and the objects to be picked up, such as bolts for example, are typically graspable from multiple orientations or properly oriented on the conveying surface, for example flat pieces are laid out on a conveyer. In some applications, objects graspable from multiple orientations are piled up on a tray but those systems do not encounter the problems associated with the use of a bin having walls.